A network such as, for example, an Institute of Electrical and Electronics Engineers (IEEE) 1394 or 1394-over-coax bridged network, etc., permits data content at a source node to be transmitted to a destination node. The network may be implemented in a home, office, etc., and may provide the capability of utilizing the services of a content provider disposed at the source node at a separately located content sink disposed at the destination node. The source node may be a content provider such as a digital video disc (DVD) player, set top box, D-VHS player, satellite receiver, etc. The destination node may be a content sink such as a receiver, monitor, etc. For example, an individual may have the DVD player located at one portion of a home such as the living room as the source node and a separate monitor or receiver located at another portion of the home such as that individual's bedroom as the destination node. The individual will be able to watch DVD programming from the DVD player of the living room in the individual's bedroom via the separate monitor or receiver.
The source node and the destination node are connected to each other via an apparatus or device such as, for example, a 1394 bridge, network switch, Ethernet, etc., which will be referred to generally as a network bridge. Particularly, the source node may be connected to a first bridge and the destination node may be connected to a second bridge via an existing cable infrastructure. The media access control (MAC) layer of the first and second bridges can adopt time division multiple access (TDMA) for exchanging data in which a superframe is generated for transmitting and receiving data as in an IEEE 802.15.3 MAC layer.
In accordance with the demands of contents providers, many high quality digital devices such as DVD and HDTV devices use a digital transmission content protection (DTCP) standard such as DTCP-1394 or DTCP Internet Protocol (DTCP-IP) for digital rights management. Particularly, the DTCP standard provides for an authentication process to ensure that the content is being sent to a trusted device. In addition, many content owners require verification of localization between the source node and the destination node to ensure that the content is being distributed at the intended source or network rather than at a remote location or being broadcast. DTCP-IP provides localization by setting a maximum number of routers or switches along a packet path (hop count) and by requiring a 7 ms measurement from transmission of a packet from a source node to reception of a reply packet from the destination node, which will be referred to as round trip time (RTT) measurement, for standard definition content. A 2 ms RTT measurement may be required in the future for high definition content. Presently, DTCP-1394 has not required localization because, for example, the 1394 cables have limited length and it has not been possible to connect 1394 cable over the internet.
However, as mentioned above, the MAC layer uses TDMA-based superframes for exchanging data. The TDMA-based superframe may have a length of up to 65 ms, with only certain slots allocated for providing communication from the source node to the destination node and for providing communication from the destination node to the source node. Therefore, there will be latency from the time a packet arrives at a superframe to the time that it is transmitted over a particular slot to the destination node and from the time a response arrives at a superframe to the time it is transmitted over a particular slot to the source node. That is, the inherent nature of the TDMA-based superframe may render it difficult to achieve the minimum round trip time required by the content at the source node, thereby preventing verification of localization between the source node and the destination node.